1. Field of the Invention
The present invention relates to a camshaft system for operating cylinder poppet valves incorporated within internal combustion engine, where the camshaft has a controlled timing or phasing, and with lubricating oil serving the dual function of not only operating camshaft phaser, but also providing lubrication for a portion of the camshaft.
2. Background Information
The lubrication of moving parts within an internal combustion engine is both necessary and costly. Of course, lubrication must be furnished to prevent undue wear of moving parts, but also to provide a mechanism for facilitating heat transfer. Lubrication is costly because a pump and a transfer network must be provided, with the pump having sufficient capacity to service a wide variety of moving parts and engine operating regimes. In the case of moving parts such as a camshaft, this lubrication requirement extends to lubrication of the camshaft's thrust faces. Usually, camshaft lubrication needs dictate that drilled passages be provided in opposing sides of the structures to which the camshaft's thrust surfaces abut. However, this necessitates that the oil pump be sized for a significant leakage path; this means that the pump must have greater capacity and, also, that the pump will absorb more power.
It would be desirable to be able to furnish lubrication to camshaft thrust faces without the need of providing additional oil pump capacity and without the need for providing specialized drilled or cored passages within a cylinder head of an overhead cam engine.